By the way, if a project was already started before the contest, but all that has been showcased are graphics and a dynamic tile generator in some forum topics with no download available, then would such project be eligible for the contest? I had an idea in mind just now, but I already posted some graphics in the pixel art sub-forum here and I showed a video containing extra graphics to some people.

I've always treated it as engine code is usable. As long as it's a new game/project/not looking like something released before. Eg: An old engine can be reused as long as you add enough content that its not a copy paste job. So in this instance if you add enough to the tile map generator that its not just a tile map generator there shouldn't be any issues IMO. But don't quote me on that.